Re: Upgrading Shepherd services

[Ludovic Courtès]

Hi Felix,

Felix Lechner via "Development of GNU Guix and the GNU System
distribution." <guix-devel@gnu.org> skribis:

> I have a lot of custom Shepherd services.  Every so often I make a
> mistake that stalls the step in 'guix deploy' that upgrades Shepherd
> services, but without any error messages.
>
> Unfortunately, I can also no longer run 'herd status', which likewise
> hangs, or 'reboot'.  How may I debug such issues in my operating-system
> declaration, please?

The standard service constructors are de-constructors cannot block
shepherd entirely (at least not AFAIK).  So my suggestion would be to
first look at any service you’re using that has a custom ‘start’ or
‘stop’ method doing weird things; make sure none of them can block.

Another thing: when shepherd is blocked, try “sudo strace -p1” so see
what syscall it’s waiting to complete (that’s the likely problem).

In addition, check the last lines of /var/log/messages so see what
shepherd was trying to do before blocking.

HTH!

Ludo’.